CN-121997029-A - Method for identifying and positioning damage of top tension riser based on wavelet packet transformation

CN121997029ACN 121997029 ACN121997029 ACN 121997029ACN-121997029-A

Abstract

The invention provides a method for identifying and positioning damage of a top tension riser based on wavelet packet transformation, which belongs to the technical field of intelligent monitoring of marine structures, and comprises the steps of firstly collecting and preprocessing vibration acceleration response signals of preset nodes of the riser, then taking a number of Bei Xixiao waves of 6 steps as parent wavelet, setting the number of decomposition layers of 4 layers of wavelet packets, iteratively decomposing the preprocessed signals through a Mallat algorithm to obtain 16 frequency band component signals, then calculating wavelet packet component energy of each node under 16 frequency bands by using sensitivity of the structural rigidity damage based on Xin Jihe wavelet packet energy, solving the curvature of the wavelet packet energy of each node through a variable secondary difference value, finally taking the curvature and the curvature of the same node of a healthy riser as a IWPECD index, and finally carrying out 5-point sliding average smoothing analysis on the distribution rule of the analysis index along the length of the riser, wherein the peak corresponding node is the damaged position of the riser, thus realizing effective damage positioning of the top tension riser.

Inventors

LI XIAOMIN
SUN JUNLONG
LI FUHENG
HE BOWEN
JIANG YUFENG
ZHANG CHENGQIANG
LI KETAN
LV SHUANGJUN
YANG TIANCHENG
WANG JIAJU

Assignees

中国海洋大学

Dates

Publication Date: 20260508
Application Date: 20260212

Claims (7)

1. The method for identifying and positioning damage of the top tension riser based on wavelet packet transformation is characterized by comprising the following steps of: s1, collecting and preprocessing vibration acceleration response signals at preset node positions of a top tension riser; S2, selecting a plurality Bei Xixiao of Daubechies with the wavelet order of 6 as a mother wavelet function, setting the decomposition layer number of a wavelet packet as 4 layers, and respectively carrying out iterative decomposition on the vibration acceleration response signals subjected to pretreatment based on a Mallat algorithm to obtain 16 frequency band component signals; S3, calculating wavelet packet component energy of each node of the top tension riser under 16 frequency band component signals by using sensitivity of the wavelet packet energy to structural rigidity damage based on Xin Jihe wavelet packet energy in an arch bridge damage identification method; S4, solving and calculating the wavelet packet energy curvature of each node of the top tension riser by adopting a secondary difference value of a variable based on the extracted wavelet packet component energy of each node; And S5, taking the obtained wavelet packet energy curvature of each node and the wavelet packet energy curvature obtained by the method from S1 to S4 of the same node of the top tension riser in a healthy state as a difference, obtaining a wavelet packet energy curvature difference IWPECD index, analyzing the distribution rule of IWPECD index along the length direction of the top tension riser by adopting a 5-point sliding average smoothing algorithm, and identifying the peak position in IWPECD index distribution, wherein the node position corresponding to the peak is the damage position of the obtained top tension riser.
2. The method for identifying and positioning the damage of the top tension riser based on wavelet packet transformation as claimed in claim 1, wherein the S1 is characterized in that a minimum mean square error LMS adaptive filtering algorithm is adopted to preprocess an original acquisition signal, environmental interference noise is eliminated through iterative calculation, active components related to the damage of the riser in the signal are reserved, and a vibration acceleration response signal with standard-reaching denoised fidelity is obtained.
3. The method for identifying and positioning damage to a top tension riser based on wavelet packet transformation as claimed in claim 1, wherein the low frequency component and the high frequency component of the signal in each decomposition iteration process of the Mallat algorithm in S2 are equally frequency-band divided, so that the effective frequency range of riser vibration is completely covered.
4. The method for identifying and positioning the damage of the top tension riser based on wavelet packet transformation as claimed in claim 1, wherein when the wavelet packet component energy of each node under each frequency band is calculated in the step S3, the specific steps are as follows: Provision for provision of The number of layers decomposed for wavelet packets, called scale parameters, is defined The signal energy of the layer is: (1) Wherein the method comprises the steps of And Wavelet components of signals of each frequency band obtained after the signals are decomposed by wavelet packets; Time is; The 16 frequency band component signals obtained in the step S2 are called initial signals; Is that Signal energy of the layer; initial signal Through the process of After the layer is decomposed, by decomposition Summing the individual constituent nodes to obtain Energy of (2); the wavelet packet component energy is calculated, and the calculation formula is as follows: (2) Wherein the method comprises the steps of For energy stored in the corresponding band component signal; is a modulation parameter; Determining a time domain integration method as a trapezoid integration method, and obtaining the time domain integration operation of the frequency band component signal; When the mother wavelets are orthogonal, the total signal energy is expressed as the sum of the wavelet packet component energies, expressed as: (3) Wherein the method comprises the steps of Is a modulation parameter; Is a scale parameter; For wavelet packet component energy; Is that Signal energy of the layer; and uniformly mapping the energy values of the 16 frequency bands to the [0,1] interval by adopting a normalization formula, and finally obtaining the normalized wavelet packet component energy of each node under the 16 frequency bands.
5. The method for identifying and locating damage to a top tension riser based on wavelet packet transformation as defined in claim 1, wherein when the wavelet packet energy curvature of each node of the top tension riser is calculated in the step S4, the method specifically comprises the following steps: Taking the obtained normalized wavelet packet component energy of each node as basic data, adopting a variable secondary difference formula, solving the initial value of the wavelet packet energy curvature node by node, wherein the calculation formula is as follows: (4) Wherein the method comprises the steps of Is the node spacing; 、、 respectively corresponding modulation parameters 、、 The wavelet packet component energy below; The initial value of the energy curvature of the wavelet packet is; If the preset node spacing of the top tension riser is unequal, correcting the node position and the corresponding energy data by adopting a cubic spline interpolation method, wherein the interpolation node density is set to be 2 times of the original node density, and the corrected node spacing distribution is ensured to be smooth; The curvature calculation errors are controlled within a certain error through the pre-preprocessing of the node data, the multiplexing of the node spacing parameters, the fixed point operation instead of floating point operation and other algorithm optimization, so that the total curvature calculation duration of the nodes is ensured to meet the real-time monitoring requirement, and finally the wavelet packet energy curvature of each node is obtained.
6. The method for identifying and positioning damage to the top tension riser based on wavelet packet transformation according to claim 1, wherein when the damage position is obtained in step S5, the method comprises the following specific steps: step1, based on collecting vibration acceleration response signals under a healthy state top tension riser, obtaining wavelet packet energy curvature of each node of the healthy state top tension riser, eliminating influence of temperature change on curvature values by adopting a temperature compensation algorithm, and obtaining a wavelet packet energy curvature difference IWPECD index by differentiating the curvature of the healthy state and the damage state, wherein the formula is as follows: (5) Wherein the method comprises the steps of 、 Wavelet packet energy curvature for healthy and damaged states, respectively; Step 2, smoothing the obtained IWPECD indexes by adopting a 5-point moving average smoothing algorithm, so as to ensure that the fluctuation amplitude of the IWPECD indexes after the smoothing does not exceed a specific amplitude; Step 3, drawing a distribution curve of IWPECD indexes along the length direction of the top tension riser after the smoothing treatment, and analyzing the change rule and the peak position of the curve; step 4, setting a threshold value to be 3 times of the standard deviation of IWPECD indexes in a healthy state, and screening peaks exceeding the threshold value in a distribution curve; And 5, judging the node position corresponding to the super-threshold peak value as the damaged position of the top tension riser.
7. The method for identifying and locating damage to a top tension riser based on wavelet packet transformation as recited in claim 1, wherein the IWPECD index fluctuation range after the smoothing process is ensured to be not more than a specific range of + -5%.

Description

Method for identifying and positioning damage of top tension riser based on wavelet packet transformation The invention belongs to the technical field of intelligent monitoring of marine structures, and particularly relates to a method for identifying and positioning damage of a top tension riser based on wavelet packet transformation. Background Top tension risers (TTR structures) are elongated pipes that connect an ocean surface platform to a subsea wellhead and transport oil and gas resources between the two, and are a common type of marine riser. For the TTR structure, no effective method is found at present, and the damage condition of the TTR structure can be rapidly and accurately identified. At present, two methods are widely applied to damage detection of a structural system based on vibration, one is a method based on a mode, wherein a mode parameter is a function of physical characteristics of the structure, and the natural frequency, vibration mode, damping and other vibration characteristics of the structure can be influenced by the change of physical characteristics such as mass, rigidity and the like of the structure. Another method is based on a statistical method of measured data, the time course of recorded vibration, strain or acceleration and other related data is checked, information changing along with the start of damage can be directly extracted from the data, and the performance of damage detection is greatly dependent on the selection of damage sensitive characteristics. However, no vibration-based damage identification method is currently available that can give accurate results for all structural systems and damage levels. Therefore, the method for quickly and accurately positioning the TTR damage and quantifying the damage degree of the TTR damage is found, and has important significance for avoiding economic loss and environmental pollution caused by damage of the vertical pipe. Disclosure of Invention Aiming at the problems, the invention applies a wavelet packet transformation method to process the vortex-induced vibration response signal of the top tension riser under the excitation of lift force, introduces the damage Index of Wavelet Packet Energy Curvature Difference (IWPECD), realizes the damage positioning of the top tension riser, and simultaneously analyzes the influence of different factors on the applicability of the method. The invention provides a method for identifying and positioning damage of a top tension riser based on wavelet packet transformation, which comprises the following steps: s1, collecting and preprocessing vibration acceleration response signals at preset node positions of a top tension riser; S2, selecting a plurality Bei Xixiao of Daubechies with the wavelet order of 6 as a mother wavelet function, setting the decomposition layer number of a wavelet packet as 4 layers, and respectively carrying out iterative decomposition on the vibration acceleration response signals subjected to pretreatment based on a Mallat algorithm to obtain 16 frequency band component signals; S3, calculating wavelet packet component energy of each node of the top tension riser under 16 frequency band component signals by using sensitivity of the wavelet packet energy to structural rigidity damage based on Xin Jihe wavelet packet energy in an arch bridge damage identification method; S4, solving and calculating the wavelet packet energy curvature of each node of the top tension riser by adopting a secondary difference value of a variable based on the extracted wavelet packet component energy of each node; And S5, taking the obtained wavelet packet energy curvature of each node and the wavelet packet energy curvature obtained by the method from S1 to S4 of the same node of the top tension riser in a healthy state as a difference, obtaining a wavelet packet energy curvature difference IWPECD index, analyzing the distribution rule of IWPECD index along the length direction of the top tension riser by adopting a 5-point sliding average smoothing algorithm, and identifying the peak position in IWPECD index distribution, wherein the node position corresponding to the peak is the damage position of the obtained top tension riser. Preferably, in the step S1, a minimum mean square error LMS adaptive filtering algorithm is adopted to preprocess an original acquisition signal, environmental interference noise is eliminated through iterative calculation, active ingredients related to riser damage in the signal are reserved, and a vibration acceleration response signal with the standard-reaching fidelity after denoising is obtained. Preferably, the low-frequency component and the high-frequency component of the signal in each decomposition iteration process of the Mallat algorithm in S2 are both subjected to equal-frequency-band division, so that the effective frequency range of the riser vibration is completely covered. Preferably, when the step S3 calculates the wavelet packet compo